The whole nebular idea even to be considered depends on taking the big bunk creationism for granted. That includes re-ification of the notion the Universe which means treating the Universe as a single, finite object uniformly evolving in linear time. That is, starting from a singularity that is everywhere, going next to the cloud of the simplest elements which in its turn collapses into the first stars and so on. No reason to take that for granted. That is not possible at all. Cosmologically, time is another measurement of distance. That means distance in every direction as measured from any possible relative location. No common shared past for each and every location and no uniform evolution is implied by that at all.
The stars and planets indeed may be recycled in any case so you are right to an extent. Though the actual process may never have started and its mechanism might have nothing to do with gravitational collapse. Not so long ago, I have stumbled on an alternative hypothesis of planet formation that really impressed me. The hypothesis is very rough and might be off in many details but its general direction of thought is very interesting. It proposes that stars and planets are the same thing at different stages. That is, that planets are nothing but cooled stars. That would mean that giants like Jupiter are on their way of becoming earth-like and so on. Jeffrey Wolynski is the guy who came up with the conjecture.
Well, yes, that is a difficulty with the hypothesis if the earth-sun mass relation is correct as it currently stands. Heavier elements in the sun would then result in a few thousands planets like earth. The author contest the relationship while myself, I have not reached a conclusive opinion on that. I can't say until I understand much better than I do what mass and gravity is. Anyway, the current understanding of what drives the sun and other stars and how exactly is not the last word to be spoken to be sure. What though I have no doubt about is that the whole big bunk framework to stellar and planet formation is definitely pure fancy and will be completely abandoned in a few decades from now. Whatever is the case, the Sun is not the second or third generation of stars in existence. The scenario where the Milky Way is as old as the existence itself is certainly all the way off. One might be much older than currently estimated, the other may be incompatible in principle with the idea of measurable age. The current figure for a single spin of the galaxy is 250 million of years. Spinning is how it has got its into its present shape. Forty odd spins all in all is extremely unlikely, methinks.